Caring for Houseplants in Northern Climates - This University of Minnesota Extension site talks about the seasonal fluctuations in light, water, temperature,
humidity, and nutrient requirements of houseplants that may be experienced by northern growers.

Caring for Houseplants - this University of Missouri Extension page has information on watering, lighting, temperature, etc. to keep your plants alive and healthy

Fertilizing Houseplants - this University of Connecticut Cooperative Extension PDF has information on fertilizing houseplants.

Winter Care:

Most houseplants grow well with daytime temperatures of 65 to 75 degrees F and night temperatures of 60 to 65 degrees. Keep houseplants away from cold drafts, radiators, and hot air vents. Humidifiers are an excellent way to increase the relative humidity in a single room or throughout the entire home. Another method is to place the houseplants on trays (saucers) filled with pebbles or gravel and water. The bottoms of the pots should be above the water level. In general, houseplants require less frequent watering during the winter months than in spring and summer. Actively growing plants need more water than those at rest during the winter months. Fertilization is generally not necessary during the winter months because most plants are growing very little or resting.